This invention relates to transfer mechanisms and more particularly this invention relates to a transfer mechanism for transporting containers and drive means therefor.
Transfer or conveying mechanisms have a long history in various industries which rely on the transport of articles from one location to another during processing. There are many such constructions which are used with varying degrees of success. Most of these constructions rely on the use of an "endless" conveyor means in the form of an endless chain having individual links hingedly connected together. One such conveyor construction is disclosed in U.S. Pat. No. 3,491,873 in conjunction with a guide rail and a sanitary construction for use in the food, dairy, brewing, and softdrink industries. Other types of chain conveyors are also commonly used.
While conveyor systems utilizing chains are useful and efficient for some applications, they suffer certain disadvantages when used for other applications. For instance, when changing direction on a conveyor line, it is often necessary to locate a portion of a conveyor next to a portion of another conveyor and provide guide rails to shift the moving containers from one conveyor to the other. Then, when transferring articles from one conveyor to another, whether the articles are to proceed in the same direction or another direction, a so-called "dead plate" is required between conveyor stations. There is a disadvantage inherent in the use of a dead plate in that articles can be pushed up on to a dead plate but then, if there are no articles immediately following them to push them further on, they can remain on the dead plate without transferring to the next conveyor section. Furthermore, if the articles are of an unstable type, there is the possibility of falling over when being pushed on to, or off of, the dead plate.
Probably the most significant disadvantage of conveyors that use chains to support the articles being conveyed is that the chains have a high friction when sliding under articles that have been stopped by reason of machinery stoppage or simply backing up of articles on the conveyor. The most successful conveyor construction for avoiding this problem is that which is based on the use of a plurality of rollers instead of a flat top chain. These conveyors are particularly useful for small or inherently unstable articles because they are usually constructed in such a way that when the articles stop for one reason or another, the rollers stop, when slippage being provided at the rollers or by a slipping belt or pulley. Also, when the articles are moving, since the rollers are also moving in the same relative direction, there is no relative movement between the surface of the roller and the article.
One prior art construction of the roller type utilizes a drive system wherein a drive shaft is located below the rollers and elastomeric belts are used to transfer the rotational movement from the drive shaft to a series of roller shafts upon which the individual rollers are mounted. Thus, a number of belts equal to the number of rollers is necessary. Furthermore, for changing direction of the articles being conveyed, a complex system of rollers facing in different directions is necessary whereby an article being conveyed cannot change its direction by more than 45 degrees and a directional change greater than that requires step-wise movement. Also, due to the construction of these conveyors, it is not possible to utilize rollers of a small diameter, thereby limiting roller-type conveyors to use only where fairly large articles are being conveyed.
Another prior art construction also relies on a drive shaft located beneath the rollers and elastomeric belts connecting the rollers and the drive shaft. But this construction also utilizes slippage pulleys mounted on the drive shaft with the elastomeric belts then mounted on the pulleys.